2 Answers
2

If you run a 1MBit connection continually maxed out, you can get about:

730.5*3600/8 = 328725 ~= 328GB

per month down that channel.

HOWEVER, there is almost no chance that you'll consistently use exactly that much bandwidth throughout a month, even if you're doing something fairly consistent, traffic wise (spamming, off-site backups, etc) -- you'll still have dips and troughs. For web traffic, a 4:1 peak:average ratio is my standard ratio.

In my experience, these days it works out cheaper to buy a data allocation rather than a fixed-width pipe, as by the time you apply peak ratios and buy an appropriately sized pipe it's more expensive than just buying the data. The only time I wouldn't do that is if I was working for someone with an absolutely fixed connectivity budget, where sticking to the numbers was far more important than good performance. I'd also be looking for a new client to work for.

As far as power goes, (and this is a completely separate question that should have been asked as such) that is dependent on the equipment you're installing. There's any number of previous questions here on serverfault dealing with that issue.

so is it 328GB or 2.5TB, or are your referring to something else?
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user2659Jan 4 '10 at 1:03

730.5 => number of hours in an average month (365.25 * 24 / 12 -- I hope you can work out what those numbers are); divided by 8 is to convert bits into bytes (well, octets, anyway).
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wombleJan 4 '10 at 1:05